Start by making the raspberry syrup. Combine sugar and water in a saucepan over medium heat until sugar is dissolved. Bring to a simmer and then let cool completely (approximately 30 minutes) before adding the raspberries. Once you’ve added the raspberries to the saucepan with the syrup, use a potato masher to crush them to a pulp. Pour the resulting mixture through a fine mesh strainer to remove the pulp.

Now time for the cocktail: Add the egg white to your shaker and shake for 10 seconds without ice or any other ingredients. Then fill your shaker with the remaining ingredients, except for the sparkling water. Add ice and shake vigorously for 30 seconds.

Once thoroughly shaken, add ice and the sparkling water to your glass and double-strain the shaker contents overtop.